Case Number : Case 1476 -19 February Posted By: Guest

Hi, everyone!

After 2 months I am glad to be back.

I see a deep nodular neoplasia with vascular invasion and the cytological features reminds me metastatic neuroendocrine carcinoma. I would begin with IHQ for neuroendocrine markers.

On morphology I would discard in first place with IHQ metastatic breast adenocarcinoma. The lesion is completely round and there is lymphovascular invasion. Stromal blue mucin bothers me a bit I know it can be seen in some adnexal neoplasms and of course BCC but it doesnt look like neither of those to my eyes...

Hi Igor. Welcome back

Welcome back, Igor!

Metastatic carcinoma is my first thought too. There is glandular differentiation and lymphovascular invasion in image 3. Can see Igor's point about neuroendocrine look to the tumour, but would put  metastatic breast carcinoma as my first bet. Ofcourse immunos needed. 

I think with immunohistochemistry we can still think of metastatic adenocarcinoma. ber-ep4 is diffusely positive, EMA is positive in the apical surface of cells (lumens), ck7 and ck5 positive fits with breast mainly basal-like (aggresive), NSE could explain some focal neuroendocrine differentiation but it is highly inespecific and has been reported in a elevated percentage of basal-like breast carcinomas. CPC is important

It could be a differential but endocrine mucin producing sweat gland carcinoma is almost exclusively found on the eyelids

If this is really a case of metastatic breast adenocarcinoma, GATA3 would be a good marker to point to this diagnosis, although recently it was demonstrated that GATA3 can be positive in many adnexial primary cutaneous neoplasia. So, CPC is very important.

Morphology is more consistent with breast carcinoma...

Would favour a primary mucinous carcinoma (mixed type, with duct formation) over a metastasis from a breast primary. As Igor has suggested GATA3, mammaglobin and CK19 may be helpful to rule out a breast metastasis. In addition p63 positivity would also help in favouring a primary vs metastasis (although <10% breast carcinomas can express p63). CK5/6 positivity favours a primary cutaneous lesion, but high grade breast cancers can express CK5/6.

My report:

Adenocarcinoma, likely metastatic, could be a breast primary, possibly basal phenotype, often triple (ER, PR, HER2) negative. There is some evidence for neuroendocrine differentiation.

IHC:

Positive: EMA ++20% (glands); CK5++20%, CK7++30%, BerEP4 diffuse, CD56++5%, NSE++10%, ER+10%

Negative: p63, CK20, TTF1, synaptophysin, chromograninin. 

Comment: Thought this was unusual to have interstitial-type mucin so I put it in with the recent theme.  Agree with the excellent discussion above.